Rock pocket mice occur in rocky habitats in the southwestern United States, from south-central Utah through much of Arizona, New Mexico, Texas (western Sonora, Chihuahua and Trans-Pecos), as well as northwestern Mexico (Wilson and Ruff, 1999; Weckerly et. al., 1985; Weckerly et. al., 1988).

Biogeographic Regions: nearctic (Native )

occurs (regularly, as a native taxon) in multiple nations

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: Southwestern North America. From extreme south-central Utah south through Arizona and New Mexico to northern Mexico.

Rock pocket mice range from 157 to 188mm in total length, with a tail length from 84 to 112mm. They weigh between 10.5g. and 19.9g. The tails are long and tufted at the tip (Wilson and Ruff, 1999). Their relative size is small in contrast to other members in their genus (Vaughn, 2000). Body size varies regionally (Weckerly et. al., 1988) Pelage is grayish brown on the back with pale orange brown lines on the sides and white underneath. Hairs are coarse with weak "spines" on the rump (Wilson and Ruff, 1999). The bottoms of their hind feet are bare to the heels (Wilson and Ruff, 1999). Dental formula is 1/1 0/0 1/1 3/3=20 and cheek teeth of are ever growing (Vaughn, 2000). Sexual dimorphism is observed, with males being larger overall and in certain morphological features such as mastoid width, nasal length, and mandible length (Wilson and Ruff, 1999; Weckerly et al., 1988).

Range mass: 10.5 to 19.9 g.

Length: 18 cm

Weight: 18 grams

• Terrestrial

Rock pocket mice inhabit desert and are particularly associated with rocky areas. (Wilson and Ruff, 1999). Average home range size is 400 meters (Krebs et al., 1990).

Terrestrial Biomes: desert or dune

Comments: Cliffs, canyons, rocky gulches, old lava flows. Zonally confined to lower grasslands and deserts. Commonly found in creosote-bush, mesquite, saltbush, and creosote-bush-lechuguilla areas. Sleeping and birthing occur in underground burrows.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Rock pocket mice are granivorous, feeding on a variety of seeds depending on availability (Rebar, 1995; Wilson and Ruff, 1999). They are capable of collecting seeds in fur-lined cheek pouches. Cheek pouch volume is directly proportional to body size (Vander-Wall et al., 1998).

Comments: Diet mainly seeds; also eats insects. Stores food in burrow.

Population density was estimated at about 10-58 per ha in one area in Arizona (Hoffmeister 1986).

Comments: Reportedly inactive November-February (Hoffmeister 1986).

The breeding season begins in February or March and progresses into July. Litter size varies from three to six (Wilson and Ruff, 1999). Similar to other species of pocket mice, rock pocket mice live for a maximum of three years (Paulson, 1988). Van de Graff (1975) observed that males tend to be in reproductive condition for longer periods each year than females. In southeastern Arizona all males captured from February until September were fertile. Females are reproductively active from February until the end of July. Males in reproductive condition averaged 2.3g. heavier than those that were not (Van de Graff, 1975). During prolonged droughts reproduction is often delayed and survivorship of young is 7.3% (Paulson, 1988).

Breeding season begins in February or March and continues for several months. Pregnant females have been trapped March-July. Litter size is 1-7. See Schmidly (1977) and Hoffmeister (1986).

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

No literature available to identify negative economic importance to humans.

No literature available to identify positive economic importance to humans.

Comments: This species formerly was included in the genus Perognathus. Subgenus Chaetodipus was elevated to full genus status by Hafner and Hafner (1983); this treatment was supported by a phylogenetic analysis of Heteromyidae based on myology (Ryan 1989). Chaetodipus was accepted as a full genus by Jones et al. (1992), Patton (in Wilson and Reeder 1993, 2005), and most other authors subsequent to Hafner and Hafner (1983). In a phylogeny based on molecular data, Riddle (1995) found support for the monophyly of Chaetodipus, including C. formosus, relative to Perognathus.

See Weckerly et al. (1988) for description of new subspecies from Pedro Armendariz lava field, New Mexico.